Heudbrink



July 22 1924. Re. 15,873

J, A. HEIDBRINK ANESTHETIC APPARATUS Original Filed Nov. 25,1911 5 s s 4 f/vvn/Tok; HEIDB'RWK Y Af oR/QEY Reissued July 22, 1924.

UNITED STATES- p Re. 15,813

JAY A. @HEIDBRINK, or ninnnAroms; MINNESOTA.

ANESTHFJTIC APPARATUS Original No. 1,309,686, dated To all whom it may concern:

Be it known'that I, JAY A. HEIDBRINK,

a citizen of the United States, and a resident of Minneapolis, in the county of Hennepin and State of Minnesota, have invented certain new and useful Improvements in AnzestheticfApparatus, of which the following is a specification,

.My invention relates to apparatus for producing a state of anesthesia'by the inhalationof a mixture of nitrous-oxid (N 0). and oxygen (0). VV'ith the proper mixture of these two gases anesthesia may be produced and maintained for a length of time sufficient to perform the most delicate I and difficult surgical or dental operation with a minimum of nausea or other bad 'effects resulting and with no danger to the life of the subject.

The vital point in this method is to secure a constant and uniform flow of .each'of the gases so as to provide a mixture havin I a redetermined proportionof the gases an W ich mixture will at all times be uniform while the same is being delivered and administered to the patient. It is the object of this invention to provide areliable apparatus which will so uniformly deliver amixture of the gases in a fixed proportion thereof or in exactly predetermined relation. Other objects of the invention are to change the proportions or quantitative relations of the gases in the mixture delivered at will, to indicate the proportionsat all times, to electrically warm the gases and indicate the temperature of the mixture delivered and "to provide details of construction for carryingiout these objects.

\ particular means of effecting the particular objectsof the invention consists in providing separate and independentconnections or passageways from the respective sources of supply of oxygen and otnitrous oxid with the mixing chamber by means of sion valve which has a connection with the Application for\ movable wall of the expansible reservoir for causing the operation of the inlet valves to admit and shut off admission of gas 'to the respective passageways and reservoirs.

.To enable those skilled in the artto which my invention'relates to more fully understandthe construction, operation and advantages thereof, a particular embodiment is more fully set forth inthefollowing specification and illustrat d in the accompanying drawings in which like figures of reference indicate similar. parts throughout t e several views.

In the drawing- Figure l 'is a diagrammatic .view of my apparatus showing the pipes, wiring, etc. Fig. 2 is a top plan view of. my apparatus with the cover removed, parts being broken away and parts in horizontal section. Fig. 3 is an enlarged vertical section on theline AB, Fig. 4. Fig. 4: is an enlarged vertical section on one of the clamping attach- 'ments and a part of one of the gascylinder end view showing the door on thefront of the case partly open and the. case cover open containing the bellows partly inflated, parts also being shown in dotted lines for the sake of cleariiess. Fig. 6 is a side elevation partly in section and partly broken away. Fig. 7 is a partly sectional and part1 broken away view of the mouth inhaler. an enlarged elevation of a part of one of. the total flow or proportioning valves and will be explained further on. Fig. 9 is a section on the line E-F in Fig. 8. Fig. 10 is an enlarged elevation of another part of one of the proportioning valves. Fig. 11 is a section on the line GH in Fig. 10. Fig. 12 is an elevation of a nasal inhaler. Fig. 13 is a diagrammatic view of one of the electrical valve operating mechanisms.

containing com-pressed nitrous oxid are connected to the passageway embodying the chamber 5 in communication with the expansible member 13, and, similarly, at opig. 8 is \sshown in Fig. 1, two gas cylinders posite. sides of the apparatus cylinders 23. 4

i and12 cutout one of'each set of cylinders.

small pointer on each three-way valve indicates the cylinder being used. My in.- 'l. vention, however, does not require more than one nitrous oxid cylinder, ;as'1,' and which a continuous passageway is shown extending tofthe valve members 15 and 16 whichiadmit' thejgas to the warming and 1 mixing jchjamber 225. The regulating valves forthe' cylinders 1, 2 are indicated by nu- I Qmera lsifflfi Band for the cylinders 4 by "the. numerals 10 11 and the "expan'sible 'in the" passageways and chambers-5, 9, and each to providea reservoir. for a relatively through the passageways to the-"mixing chamber; shown, having reference to 5' ,and. 6 the bellows are relatively large containers; {while the chambers-5 .and' 9 are in the forrnfof expansionsofthe pas-.5 sageways leading from that-supply sources to the proportioning valves 16 and through" these 'valves'into the mixing charm-.-

ose, not shown, conductsjthe'inixture to inhaler attached to the subjectf'a nd comthe apparatus.

silbjec't to breathe regularly, and easily at valves "-15, alt'n' fit ting desirable to have .the -mixtu.re' at such wright pressure that it will when subject being anesthetized inhales. .Tw o pipes 21322, together with their cut- "jsion chambers 5, 9'. Tubes, not shown; conneetingwith these pipes 21,122, pass to the jnouth'inhaler shown in- Fig.7, where they through the regulating valvesi27. 28, a nd the pipe 30, one endofjwhich is placed injthe open mouth of the subject. This month in haler is especially designed. for operations in the mouth and head when it is necessary to keep the 'subjects mouth open dui'in the operation ,-as in dental work. Thesu 'jectl 50 may be anesthetized with.. a nasal inhaler even though thefrnouth be open, the subembers 13, 14 are in the form of bellows devices which are identical in construction 1 and are designed to maintainiequ'al pressure .alarge volunieof gas at" a relatively low pres- 'may be turned. to instantly sure from 7 which said gas is' delivered her 225 around the warming lamgl'? and prises the gas administring" assageway of "all times. and also-toirelieve any excessive pressure that 'jmig ht'pass the prop'ortloning "i y flw thr uah erid g p p la oil valves 23, 24, connect; with the fex'panj connect with the" two pipes25, 26 ,leading flow through" thejvalve. p The proportion'ofthe respective gases'in through the mouth and provision is thus made to keep the mouth filled at all times with the proper mixture of anesthetizing reathing a sufiicient amount of airto counteract the anaesthetic. I .one oxygen cylinder, as '3, from each of y from the expansion chambersb, 9, and do not pass through the main mixing valves 15, 16. Inthis instance the gases are taken directly from the-expansion chambers in order tof :getasufiicienti' pressure to cause them to flow into fa'rid'fil l-the mouth of the subject at all times;

If one of the cylinders 1, 2, containing nitrous-'oxid should becomeexhausted d ur-- ing' an operation, the, three-way valve "6', lace the other cylindeni-n operation. The t reerway valve l2,- may blusedjto. change the oxygen cylinders in the-same manner.

The two "tot-a1 new valves 15, 16,; which flare also'the proportioning valves, are

'controlled iby' *af'coinmon s haft''.3l Fig. 2) and-operate together asone valveb Each of these'lvalvesil5, 16, is made 11 "of two main 'part's'32 33,' which are cylin rical in shape eachhaving three equal slots and three ex tensions. These-parts are shown in detail in F 8 1:0 .11. Eachoif thev three extensions around the. periphery of the two parts 32j,j33;, fits ,snngly'into the slots in the other part and j when put 'togetherform a closed hollow; :e ifniariea1.= valve which ii-ntirely closesbotli 'ot the ports 34, 35 in thevalve 'fichaniber *36 (Fig. 2). A regulating screw passing through the valveichamber head 38, engages with itsl thread'ed zportion the threaded-center openingof the pm 33 of the'valve which is therebylonfitudinally movablein thechamber" 36. ;will 'thus 7 be seen that when the screw 311 is turned the valve part 33 will be withdrawn sligthly from the valve part 32, leavingjthree open ports aroundthe periphery of the valve as shown best in Fig. '1. 'Ea'ch of these ports willextend. around done-sixth of the circumferenceofthe VaIVeQor-siXtydegrees. The width of these ports depends upon the amount the screw. 37 tiirned,-- its pitch, etc.- .By turning the shaft 31 together with the-valveparts two of'tliese'openin szs will be brought opposite the two ports 34, 35 in 121) the valvelcasegthus permitting the gas to the mixture is governed by the distance the apart of t e sets of valve parts 32, 33, re-

openin between the valve spectively for the oxygen and the nitrous oxid, determines the respective widths of the segmental cylindrical areas and in that way fixes the proportionof gases going to the mixing chamber. If it is desired to de-. livera mixture of ten parts of nitrous-oxid to one part of oxygen the o ening between the valve parts 32,33 of tlie nitrous-oxid valve 15.is made ten times as large as the arts of the oxygen va vs 16, that is, the cylindrical segment or, nitrous oxld delivery will be ten times as wide as and have ten times the area of the cylindrical segment for oxygen delivery.

Both valve members 15-and 16' are turned by the common shaft 31, which has the effect of increasing in the same amounts the lengths or circumferential extent of the segmental cylindrical delivery openings for the nitrous oxid and the oxygen respectively.

The valve chamber. head 38 is integrally connected to the valve part 32, and shaft 31,

' the being indicated by a pointer 135.

and revolves therewith. A small indicator point on the screw 37 shows at all times by means of a scale 39 on the valve chamber head 38, the proportionate amounts of opening of the ports of. the valves, and since the two gases are at the same pressure this will give the exact mixture delivered.

Although two ofthese adjusting screws 37 are shown (one for each valve 15, 16), only The nitrous-oxid valve will be fixed at a certain opening (i. e. a certain distance be-' tween the valve parts), the scale and indicator point of the oxygen valve indicating the percentage of oxygenin the total mixture delivered.

In order to determine the proportions of ases in the mixture delivered by the mout inhaler the short screw valve 27 is opened a certain amount and a cap 40 placed over it to prevent its being tampered with.

The percenta e of oxygen in the mixture is then regulate by the hand valve 28 and indicated by the pointer 41. A butterfly valve 134 in the mouth pipe 30 serves to regulate the amount bf mixture delivered, the amount Nitrous-oxid and oxygen may be purchased on the open market compressed in cylinders 1, 2, 3, 4, as shown. These cylin-' ders have a standard square neck 42 (Fig. 4), and are rovided with a needle valve 43 which may e operated by. a small hand or gear wheel. As it is of the utmost importance to keep a constant supply of both nitrous-oxid and oxygen during a prolonged operation it is advisable to have several extra cylinders on hand to replace any that may be emptied. As my apparatus is provided with means for holding two of each of the cylinders, when one of either kind being re one will in practice need to be used.

is discharged totally the other may on and used while the discharged cylinder is laced by-a full one.

Clamping attachments 44, 44 (Fig. 2) are provided for each of the cylinders in use in the apparatusand extra clamps are provided for all extra cylinders'on hand. This clamping attachment comprises a frame or yoke 45 (Fig. 4), which goes around the square neck 42 of the cylinder; a clamping 'screw 47, with an. extension 48 at its outer end to'support'a part of the weight of'the cylinder when in use; a nipple 49, extending into the opening in the square neck 42 of the cylinder; and a curved hollow neck 50 extending outward from the nipple 49, and adapted to be quickly clamped in place on the apparatus by means of a clamp 51, one of which is located over one of each of the discharge openings 52, 52, in the machine proper. Gaskets of rubber or some similar material are provided to make tight joints around the nipple 49, and the outer end of the curved neck 50. Thus the clamp 51 may be quickly raised, the drum and clam ing attachment lifted out, and another rum or cylinder and clamping attachment clamped in position in a very short time. The clamp 51 is swiveled on its bearings 53,

'53, as shown in Fig. 3.

inhaler. For this purpose an incandescent electric light 17 is placed in "such a position that the mixture must pass over and around it, and in so doing absorb suflicient heat from the light bulb to warm the gases to a normal temperature. A small opening 54 (Fig. 2) is made in the top covering plate 55 of the apparatus directly over a. portion of the light bulb and provided with a glassclosure to enable'the operator to know at all times that the light is burning A small thermometer 18, with its bulb interposed in the warming chamber, is always in plain view of the operator showing at all times the exact temperature of the mixture as it passes to the inhaler.

It is very evident that in order to obtain a mixture of predetermined proportions of the respective gases by means of the relative sizes of openings in the main valves 15, 16,

1 the pressure of tlic nitrous-oxid in the expanbe turned the hinges and telescoping arrangement is to provide means for carryi thejfgasas into the hinged'lid where the be ows are located, These bellows are guided, in their movements by light lazy-tongs devices 126, 27,-. and'may carry weights to givevariationsfof pressure to thecontents as'desired, I

'In'order to-maintain' a normalfamount of the gases inthe; bellows, at all times an autosmall pim'ons 61, 62 integrally mounted matic controll is 'arranged t'o govern the fiow of the gaseslthrough the valves 7,48,10, .11 These valves,- desiglnated 43 and shown :more

plainly Fig. 4, ave-a large stem extendng 11 wardp-LThese stems 58, 58,:(Fig. '2)

are a apt'ed' to beengagedby hand oreat,

wheels 59,- ,6Q,i whicli ln'tu'r'n are engage 'plnlons are so. arranged-as to engage the wheels 59, 60, whenplaced' position to: operate either one of the two cylinders-at each end of the apparatus, ThilS, if the three 89, pressin shafts 63, 64

way valve6 were turn'edto discharge from the-cylinder '1, the wheel .60

placed onthe valve stem 58 of the same'c'yl- 'inder 1. Onthe lower-ends of, thefpinion, Fig. 6) are woi'm ,wheels '65,. 66 -which are en aged by wor-ifi's'f 67, 68 mounted integraly to rotate with other worm wheels 69, 70. These worm wheels 69,

70, are engaged by worms 71, 72, which are integrally mountedon shafts 73,.74,*on the} opposite ends of which are mountedfric-- t on wheels 75, 76, one of which 75, mounted on the shaft 73, with: the worm 71, is shown in'Fig. 5.

These friction wheels 75, 76, areoperated,

by the yokes 77, 78, and the armatures 7 9,1 8.0; 85, .86, as is shown more ainly in Figs li and 13. The coil spring 8 7 the armature V7.9 keeps it normallyat' its outer limit of travel as shown in the drawing. When the bellows 14 is partially exhausted the stop 88 (Figs. 1 and 5) comes in contact with the upper contact spring ofthe switch it against the lower contact ring an closin' the electrical circuit t ough the solenoi 81, thus drawing in the armature 79 and yoke. 78.

The weight of the heavy yoke 78 resting upon the upper part of the friction wheel causes itto revolve a part of a revolution and thus operating the train of worm wheels and gears to turnthe pinion 61 and thus open one of the valves 10, 11, in the cylinder necks according to which cylinder is in use.

Anotherfswitch 91, located near the yoke 7 8, is interposed in circuit with the solenoid 81 and operated by a small projection 92 on the slide 93. This slide93 is operated by the yoke 78 striking upon small projections 94,

95, at either end of the slide 93.

--As the armature is drawn in to its inner limit of travel the yoke 7 8, striking the proj'ection 95, on'the slide 93, moves it to the would then be l-thereof, in its pushing against right. The projection the slide 93, be-

ing thus withdrajvvne-f rom contact Withthe lowersp'ring o-f-the' swijtch 91', the springs of thisswit'ch are permitted 0 come apart and open the solenoid-circa," i -The armature 79 is thus, released an-d the coiled spring 87,

-ai'mature, now pushes the armature out again to its normal'position. Asthe armature 79 is pushed out by the spring 87 the outer end of the yoke 78, striking against-the project-ion. 94,"moves the slide 93 back to itsnormal position, causing the contacts of the switch '91, to again close the circuit operating the'solenoid 81-;and thus to repeat the cycle of operations until the oxygen liberated by which has been compressed by the indrawn A the opening of one ofthe valve's 1'0, 11, in the noted in the operation of g. 6, thus-raising the yoke high enou h thatitsgfpperfarmldoesfnot rest upon t e "frictionl'wheel 75,-;yet not so high that its lower arm comes inpontact'with the under side of; the wheel'75, In his way no im ulse [is given the wheel on; the outward stro e of th'e'armaturei- "The'cam96 is assisted by a leaf-- spring engageable beneath a portion lifting movement, said s ring being compressed by the turningfof't e ec- *ce nitiic through friction of the arm 78 upon .t-he'same when said arm is nioved under the influence of:so1enoid 81..-.;

oxygen the sto'p.,88, coming in (:ontac't with the lower spring of'the switch- 90, causes it to come in contact witlrthe upper contact" spring, and thus closefthe double solenoid 'Cllclllll as is plainly'shotwn in Fig. 1, oper-' 'ating the lower solenoid 83 at the same.

Whenthe-bellows let-is -nearly filled with time the upper s0lenoid'81 is operatedzi- The armature 85 of the lower asolenoid 83,]

carries a small roller at its upperv endwhich is pressed against the underside of the yoke. 78, when both solenoids are operated and raising the'yoke untilits lower arm presses against the underside of the friction wheel "75,- thus causes the. ,friction wheel to be turned in an opposite direction to that in hich it turns when only the upper sole noid 81 is operated. a

The two solenoids operate together in this manner until the oxygenis turned ofl' enough to permit the bellows 14 to lower and release tlie switch contacts 90, which, coming apart, I open action. a The bellows 13 regulates the flow of the circuit andv thus stop the nitrous-oxid from the cylinders 1, 2, in

the same manner by means of its solenoids 82, 84, armatures 80, 86, yoke 77,, friction wheel 76, and worm gear train to the valves -7, 8, and the switches 97, 98, 99, correspondii} to the switches 89, 90, 91, of the oxygen After the gases have passed the proportioning valves 15, 16, they are at liberty to fully expand by flowing freely into the li ht suspended bag and thus practically afi pressure'is relieved, the bag 20 also acting as a reservoir to supply the intermittent breathing of the subject. To the lower part of this supply bag 20 is attached a light metal plate 100, which, when the is almost empty, rests upon the two i switch contacts 101, 102, and bridging across 104 and yoke 105 an 1 needs of between them closes the circuit through the solenoid .103 which 0 crates its armature friction wheel 106, together with a suitable worm ear train to open the total flow or main mixing valves 15, 16, in the same manner that the solenoids 81, 82,- open the nitrous-oxid and oxygen valves 7, 8, 10, 11;

- The switch thus closed by the plate 100' corresponds in its action in its circuit to the switches 89 and 98 in their respective circuits already described. When the bag 20 is filled it presses 1i htly against the switch 206, shown plain y in Fig. 6, and closing it causes the solenoids 103, 107, to

be operated togpther in the manner already described in t e-operation of the oxygen regulating s0lenoids 81, 83, and thus slowly close the mixing valves 15, 16, until the bag 20, becoming artly exhausted, releases the switch 206. he switch 109 in its functions corresggids to the switches 91 and 99 in their ctions.

Thus, the quality of mixture going to the patient is automatically kept uniform and the rate of theflow of the mixture is auto determined and neither of these a of the machine requires any of th joperators-attention. The proportionbeing .set to determine "the rate 'fl w'iojf the respective gases into. the mixamber and the mixture bag 20, the I v 've will be caused to continue 601 ow in t ese proportions from the reservoirs formed by the expansible bellows membars, which fiow will always be constant because as gasis taken from these reservoirs it will constantly be replenished by the'automatic opention of the delivery valves effected by the volume of gas inthe expansive members or reservoirs. In turn the d'elivery of this constant mixture to meet the the patient will be determined by the volume of gas in or taken from the mixture container 20.

The electrical current may be derived afi al y E I from any, convenient source and is admitted the apparatus is to the apparatus by a double pole switch .110, and may lie-entirely disconnected by opening the switch 110. The solenoid set circuits and also the lamp circuits are controlled by individual single pole switches 111, 112, 113, 114,-by means of which solenoid set or the lamp may be turned dif at means of the thumb nut 115 (Fig. 5), mounted on the same shaft with the friction wheel 106. -Any desired form of inhaler may be used, a nasal inhaler being shown in Fig. 12. This inhaler is' attachgd to the subjects forehead and a hose from the main discharge pipe 19 on the machine proper to the intake pipe 116 on the inhaler. The mixturepassing through the intake pipe 116 enters the chamber 117 which is provided with two flexible outlet pipes 118, 119, an air valve 120 and an exhaust valve 121. These flexibleoutlet pipes 118,

119, are provided with curved nostril pieces 122, 123, which are swivel connected to the flexible outlet pipes in such a manner as tobe fitted snugly to the subjects nostrils. The entire apparatus is inclosed in a carrying case 124 provided with a deep hinged cover 57 in whichare located the bellows 13, 14, in such a manner that they may be folded into the cover when it is closed. Four telescoping legs 128, 129, 130, 131 (Fig. 2) are provided at the corners of the case 124 which slideup into the case when not in use. A door 125 on the front of the case 124 may be opened when in operation so that all operating parts will always be in full view of the operator.

I claim: 1; An anaesthetic administering apparatus comprising means including delivery valves for producing a mixture ofgases of a predetermined proportion, an expansible member for receiving the mixture as the same is delivered from the valves, and a systemof; j solenoids controlled by movement of said expansible member for. controlling the valves. a

2.- A gas administering machine compris- I ing a plurality of source's of fluid supply ewaysfor admitting oxygen 26 i volume of gas at a relatively low pressure sageway to the mixing chamber, and means caused to operate by the movement inex- 6 pansion and contraction of said flexible I, members for openingandclosing said valves to admit and shut off flow ofgas into said reservoirs. II

3'. A gas administering machine comprising a source of oxygen supply-and asource supply I each under pressure, a mixing chamber, a passagevv {Eleading from said oxygen supply "separate passageway leading from. said nitroas'ox'id I of nitrous oxid ing each of said separately mixing" chamber,. va-lve m'ec anism' trance to the mixing-lchamber-. for regal the amount of oxygen andjthe' nitrous oxid entering said; mix gj' from the respective passageways-so '-as I i produce a mixture thereofin'predetermin proportions, a valve 'inyeachof and respectively into its passagew y, ible expansion] member fhavingfig. vI with the'o x ygen passageway and flexible expansion "member: having connectio v v'vilth of said;

1n thexpressuref imposed upon. the gas by 'an 1 thenitrous'oxid passageway," e I I members constituting a reservoir fora relatively lar' e"v olume of gas ata relatively low pressure or delivery therefrom through-its r-v rs. A I gasgadministerin-g machine compris a ity. M pp e tea h sep .connected*toga supply line, anye'xconnections, afiexi ble expansion member in each of said 'connec-' tions adapted to be inflated'anddeflated by the introduction and withdrawal of gas' therefrom, and means operative from said expansion member's' for'operatmg said valves fto'cause them to admitand cutofi delivery so.

of gas to the expansion'members.

- 5. A gas administering'machine comprising an oxygen container "and a nitrous oxid container, valves for each of said containers, expansible gas reservoirs each. having conoperative from the expansion of said reser-.

voirs for operating said valves to cause/them ries of fluid containers, valves and flexible expansion chambers having connection with supply ,to' the .mixmggchamb'er for fconducthaving communication with said reservoir, Emeans... overned by'the lnflatlon and deflation' of oxid, a regulating yalfive in 'onhhamber in'each-of said connections, with each. reservoir,

in each of-Said nection with one of said valves, and means containmg oxygen and t said containers, means operative from the for delivery therefrom through I said pas- 1 said valves to provide a mixture of the gases,

expansion ;of said chambers foroperating meansfcontrolling the flow of the respective to vary. the proportion thereof, and ndicator 'for indicating the proportion. I Ii -anaesthetic apparatusfarranged to be iqii gped with a compressed gas cylinder, a regu sting valve in'commanication with the gas 'supply from-suchcylinder,anexpansi- 76 'le elastic gas bag constituting a variablepressure reservoir for -a; relatively large vol-. ume of gasat a i'el'ativeI low. pressure in free communication with t e gas administ ering passa cent the apparatus, and means governed' y the inflation of such bag for I controlling said regulating valve.

, 8, A gas admmisterin machine comprise'e p e s d n a regulating a vein communication with the as supply IO'm Such "cylinder, ankexpansi le elastic ba constituting a' reservoirfor a r 1 li e y rge volume of gas' at a'frelatively Iowa-pressure, a gas administering passage the gas II the'reservoir for controllin 'regnlatingvalve to; admit or cut 0 1n said reservoir. I 9; A gas administering-machine compris- I ing apair of compresse as cylinders one containing ygen and e other nitrous communicatibn with the gassupply irom each cylinder,'an I expansible elastic ga s bag having connection witlieach cylinder and constituting a. .reser.- voir for a relatively large volume of at a relatively low-pressure, a gas administer.- 65 ing passage having separate communication separate means .gov! erned by inflation 1 and deflation of each reservoir for controlling the respective regu lating valves'toadmit-or cut off gas "from said reservoirs; and means for varying the] pressure imposed upon'fthe gas by and in caused to operate by reason of movements of the walls offone of. said expansion membersfor operatingsaidvahes to cause them to admit and cut off delivery of gas to the respective expansion members.

; '11. A gas administerin machine comprisng a pair ofc'ompi-esse as cylinders, one

e othertm'trous 7 ing the relative rate of flowof oxid, a mixing chamber,. an independent passagewa for conducting each of said gases to t e mixi chamber, a regulating valve in each of said passageways adjacent the gas cylinder, other valve mechanism at for determinthe respective B into the mixing chamber, a flexible expansion member connected in each of said passageways intermediate said valves and each of said members constituting a reservoir for a relatively large volume of gas at the ends of said passageways a relatively low pressure, a flexible expan-- sion member connected to the mixing chamher for receiving mixture therefrom and constituting a reservoir for a relatively large isms - of the reservoirs volume of said mixture, separate means governed by the inflation and deflation of each first named for controlling the respective regulating valves to admit or cut oflgas from said reservoirs, and means governed by the inflation and deflation of said mixture reservoir for controlling the mixing chamber valve mechanism to admit or cut ofi flow of both gases into the mixing chamber and to admit or cut ofi flow of mixture from said mixing chamber into the mixing reservoir.

In testimony whereof I have hereunto affixed my signature.

JAY A. HEIDBRINK. 

